A discrete random variable $X$ takes values that are integers from 0 to 4, and
$$\mathrm { P } ( X = x ) = \left\{ \begin{array} { c l }
\frac { | 2 x - 1 | } { 12 } & ( x = 0,1,2,3 ) \\
a & ( x = 4 )
\end{array} \right.$$
What is the value of $\mathrm { V } \left( \frac { 1 } { a } X \right)$? (Here, $a$ is a nonzero constant.) [3 points]\\
(1) 36\\
(2) 39\\
(3) 42\\
(4) 45\\
(5) 48